<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>内部样式表</title>
    <style>
        h1{
            color: red;
        }
        h2{
            color: yellow;
        }
        h3{
            color: greenyellow;
        }
    </style>
</head>
<body>
    <h1>111111111111111111111</h1>
    <h2>222222222222222222222</h2>
    <h3>333333333333333333333</h3>
</body>
</html>